It is very well established practice in underground mining work, such as coal mining, tunnel excavation, or the like, to reinforce the roof of the mine to prevent cave-in. There are various types of reinforcement apparatus, the most common are of the mining bolt type. These mining bolts can consist of various designs:
1. Mechanical bolts which have a smooth round shaft--a forged head and a bearing plate on one end, and an expansion anchor at the other. (Tensioned Bolt)
2. Fully grouted resin bolts which consist of a reinforcing bar with a forged head and bearing plate on one end. The rest of the reinforcing bar is left as is. These bolts are used with polyester resin cartridges to grout around the bar and fill the annulus between the bore hole and the reinforcing bar. (Untensioned Bolt)
3. Partially anchored tensioned bolt:
A. A partially anchored (polyester resin) reinforcing bar with a frangible delay nut of various design at the bottom end plus a bearing plate. (Tensioned Bolt) referred to as a "Tension Rebar" Bolt. PA1 B. A partially anchored (polyester resin) reinforcing bar that is threaded at its bottom portion and connected to a smooth bolt on the bottom plus a bearing plate. The reinforcing bar is grouted in polyester resin. The coupling that joins the rebar to the smooth bolt on the bottom has a delay mechanism to permit the resin to be mixed and subsequently allow take up in the coupling after the resin becomes hard. A typical bolt of this design is U.S. Pat. No. 4,477,209 entitled Combo Anchor.RTM.. (Tensioned Bolt) PA1 C. A partially grouted smooth bolt that features a nut on the threaded top end to which is attached a mixing wire to mix the resin. The bottom end has a forged head, dual thrust washers, and a bearing plate. This is a tensioned bolt called the "Fastorq Bolt" patented by Dupont.
4. A grouping of bolts using either a headed reinforcing bar or a headed smooth bar with a bearing plate. At the top end is a mechanical anchor that is reinforced with polyester resin. (Tensioned Bolt) A typical bolt of this design is U.S. Pat. No. 4,655,645 entitled Spiral Bolt.RTM..
5. A smooth headed bolt with a buttress deformation at the top end which screws into a compressible plastic formable material and a bearing plate at the bottom. A polyester resin cartridge can also be used to reinforce this anchorage with the plastic tube. (Tension Bolt) U.S. Pat. No. 4,659,295 called "DYNA ROK" Anchors.
6. A long tube of high strength steel, with a slot along its entire length. One end is tapered for insertion into a drilled hole in the roof of the mine. The other end has a welded ring flange to retain a roof plate. This bolt is driven into the hole. (Untensioned Bolt) named Split Set.RTM..
7. A bolt that is manufactured from a steel tube. The tube has been mechanically reshaped to an outer diameter that is smaller. Bushings are pressed onto the ends, which are sealed through welding. The lower bushing is flanged to hold a bearing plate in place. A hole is drilled through the lower bushing and the wall of the tube to allow water to be injected into the bolt. During installation, the high pressure water causes the bolt to expand and forms it to irregularities in the drill hole. After installation, the water pressure is released. (untensioned) Bolt called Swellex.RTM., manufactured by Atlas Copco Co.
8. Screwing a threaded bolt into set resin to attain a tensioned system such as the "Clarich" roof bolt.
9. A bolt which is driven into the roof of a mine, requiring no bore hole, similar to driving a nail into wood. This is called the Pin-Set Bolt.RTM., U.S. Pat. No. 3,643,542; date of issue: Feb. 22, 1972. (Untensioned Bolt).
To further support the roof, it is advantageous to connect steel cable to the mining bolts to support the rock between the bolting sites. In the past, numerous types of cabling systems have been proposed. A company called Ground Control Ltd., located in Canada, markets a cable bolting system that consists of a cable which is positioned into a bore hole. Bonding material is then pumped in under pressure around the cable to secure it to the rock. This cabling system suffers several drawbacks. First, the bonding material must be pumped externally in a separate step after the cable is within the bore hole. Second, the bonding material must also completely fill the bore hole in order to ensure proper contact between the rock and the cable.
Another design for a cabling system is manufactured by Ingersoll-Rand Co., Inc. and is called the Scott Cable Sling System. The apparatus consists of a cable to which is permanently attached to a stiff drive member. The cable and drive member are forced into a bore hole containing a cementatios grout. Unfortunately, after installation is complete, the drive members hang below the bore hole thereby decreasing roof clearance. Further, two drive members must be wasted each time a cable is installed.
A further design for a cable-type mining support is made by Arnall, Inc. Arnall manufactures a stranded cable a length of which has an open-weave arrangement. (i.e. the strands are not tightly wound). This allows a bonding agent of cementatios grout, which is pumped into a bore hole, to penetrate into and integrate with the cable.
The present invention discloses a mining support which is less complicated and easier to install than previous cabling systems known in the prior art.